Fatal error: require(): Failed opening required. How to fix?

Question

Yii

Uploaded the site on yii2/basic to hosting.
Errors are coming:

Warning: require(/storage/ssd3/956/5536956/vendor/composer/../symfony/polyfill-mbstring/bootstrap.php): failed to open stream: No such file or directory in /storage/ssd3/956/5536956/vendor/composer/autoload_real.php on line 66
Fatal error: require(): Failed opening required '/storage/ssd3/956/5536956/vendor/composer/../symfony/polyfill-mbstring/bootstrap.php' (include_path='.:/usr/share/pear:/usr/share/php') in /storage/ssd3/956/5536956/vendor/composer/autoload_real.php on line 66

When testing on a local server, this was not the case.
All the files seem to be in the wrong place, I don’t know what I missed.

Answer 1

All files seem to be out of place

Well, no, and you have a list of what is not in place in the error.
Seems like an obvious translation to me.
My grandmother calls me recently, says: "it says press any key, what should I do?". Somewhere from the same opera)))
Learn to read mistakes, without this "kina will not be."